The G8 leaders agreed to seek â€œsubstantialâ€ cuts in greenhouse gas emissions and to give â€œserious considerationâ€ to the goal of halving such emissions by 2050 â€“ an outcome hailed as a triumph by German Chancellor Angela Merkel and British Prime Minister Tony Blair. Yet the agreement commits no one to any specific targets, least of all the United States, whose president, George W. Bush, will no longer be in office in 2009, when the tough decisions have to be made.